应急照明、道路照明灯具的端电压不宜低于其额定电压的（）。
A.85％
B.90％
C.93％
D.95％
参考答案：B
The teacher asked the students ________.
A．what they were doing at that moment
B．what were they doing at that moment
C．how are they doing at that moment
D．what they are doing at that moment
Q195碳素钢板的抗拉强度为（）MPa。
A、315~430
B、385~490
C、375~400
D、375~500
